This should be obvious to anyone with eyes too. Go look at a neighborhood with no or low through traffic and extremely old roads are in good condition. Meanwhile a nearby through-fare, unless constantly repaired and patched, will be falling apart.

Even the low traffic roads in freeze-thaw regions need constant repair. So it's not all weight related. Weight is a factor that really only matters once you start looking at commercial size vehicles.

Also look at your local bus terminals. That asphalt is damaged beyond belief, even though it sees next to no traffic.

A few dozen buses a day braking and accelerating on the same patch of street over and over will wreck it.

Thanks, asphalt!

Yeah - it happens to concrete, too ...but it takes way longer

There's a ghost town in california called new idria. Obviously, very little traffic on the road leading to it. The pavement surface is probably 50 years old and in reasonable shape except for certain areas that make you wish you brought a 4x4

In my area its immediately obvious which lanes and roads have bus routes. A three-lane each way road will have two nearly pristine lanes and one completely beat to hell. Guess which one the bus takes.

I would expect a neighborhood, even where everyone owns a semi to have significantly less wear than a thorough-faire that sees a lot of traffic. But even that didn't tell you everything. A good quality asphalt will out last a poor one pretty much no matter the conditions. We have a stretch of road near us that is always in bad shape, when another stretch, seeing the exact same traffic is in good condition.

> A 3/4-ton pickup vs your toyota camry is MAYBE a 2x increase in damage to the road.

Your source states that relative road damage between two vehicles is the forth power of the ratio of their weights.

The base curb weight of a Ford F-150 is in the vicinity of 4,600lbs. The base curbs weight of a Toyota Camry is in the vicinity of 3,500lbs. So the damage ratio is (46/35)^4 = ~3. The Toyota Camry used to be a small car, but it isn't anymore. The base curb weight of a Ford Fiesta is in the vicinity of 2,500lbs. So the damage ratio between a Toyota Camry and a Ford Fiesta is (35/25)^4 = ~3.8, and between a Ford F-150 and a Ford Fiesta is (46/25)^4 = ~11.5. So a Toyota Camry, being somewhat of a behemoth, should be paying on the order of 3.8x the amount of road tax as a Ford Fiesta.

Even so, unless we're charging the average semi truck 2500x more road tax, and vehicles of that weigh class which cause the overwhelming majority of wear, the roads will continue to be as abysmal as they currently are.

I confess I assume that we do charge trucks an absurdly larger amount of money? Is why they have weigh stations between states?

That depends on what you consider "absurdly larger" - the fee is between $1,000-$2,000 depending on the state. In some states that's not much more than you'd be paying for a nice luxury car or large SUV.

https://www.truckinfo.net/research/license-costs-by-state

I confess I had a mistaken thought that weigh stations were akin to toll booths. That is, that fees were levied based on the weight.

I can think of several problems with that thought, taking it longer, of course. :(

I'm FAR from an expert, but you aren't totally misguided. That was the original intent once upon a time, now it's more about safety. They do weigh trucks to ensure they aren't going to destroy a bridge or damage roads if they're overweight for their route - but they're primarily checking a driver's log book to ensure they aren't over hours, the truck passes safety inspections, the driver isn't transporting illicit goods, etc.

I won't presume that I know how much we're taxing semis et al., but it's clear by the road wear that it's not enough, and most of the damage is not caused by everyday drivers.

Heavy vehicles also include garbage trucks, delivery trucks, and even busses which benefit everyone. Cars have only been widely adopted for about 100 years, and it's not clear that current trends can't be sustained for another 100.

* * *

Also to prevent overweight unsafe loading, doing trafic safty inspections, smuggling prevention, and checking cargo especially to prevent cross border invasive species.

Yeah, I mostly knew these other reasons were a thing. I had not realized they were the only reason. I guess I was thinking of them more like a port of entry between states and assumed taxes were involved.

> Your source states that relative road damage between two vehicles is the forth power of the ratio of their weights.

I wonder if that only works for weights that are not too low and not too high?

For example a typical Eastern grey squirrel weighs around 50 times as much as a typical mouse, and a typical chicken weighs about 7 times as much as a squirrel.

Does a squirrel crossing a modern highway really cause over 6 million times as much damage as a mouse, and does a chicken crossing the road really cause 2400 times as much damage as a squirrel?

Yes, this is true. I’m a transport engineer and can confirm that roads are designed for a truck’s weight and cars hardly register in terms of damage.